1. Field of the Invention
The present invention relates in general to a four-cycle engine including a cylinder block having a cylinder bore in which a piston can be slidably fitted. A cylinder head is connected to the cylinder block, the cylinder head forming a combustion chamber that faces a top of the piston in a space defined by the cylinder head and the cylinder block. A camshaft is disposed on an extension of an open/close operation axis of an intake valve, the camshaft forming part of a valve actuating system driving to open and close the intake valve and an exhaust valve openably disposed in the cylinder head. An intake port is disposed in a first side wall extending along an axis of the camshaft so as to be disposed in the cylinder head. An exhaust port is disposed in a second side wall disposed in the cylinder head so as to oppose the first side wall. A head cover forms a valve train chamber that accommodates therein the valve actuating system in a space defined by the head cover and the cylinder head. A connection surface formed in the cylinder head for connecting the head cover is extended to follow along a plane that is inclined so as to be spaced further away from the cylinder block toward the first side wall relative to the second side wall. More particularly, the present invention relates to an improved cylinder head structure.
2. Description of Background Art
A known four-cycle engine, as disclosed in Japanese Patent Laid-Open No. 2004-100651 for example, has an arrangement for contributing to an even more compact cylinder head, in which a connection surface between the cylinder head and the head cover is set so as to extend along a plane that obliquely crosses a cylinder axis.
The arrangement disclosed in Japanese Patent Laid-Open No. 2004-100651 has the connection surface between the cylinder head and the head cover inclined obliquely relative to the cylinder axis, which helps make the cylinder head more compact. Stem ends of the intake valve and the exhaust valve are; however, disposed on the side of the cylinder block relative to the connection surface as viewed from the axial direction of the camshaft. This leaves room for even further reduction in size and weight of the cylinder head.